Stone disintegrator

ABSTRACT

This invention relates to an instrument for disintegrating calculi in the urinary tract by hydraulic impacts formed by electrical discharges in the liquid medium surrounding the calculi. Instruments employing this general principle are well known and they usually consist of a lithotrite having two electrodes, and a pulse forming network connected to the electrodes to provide electrical energy for forming discharge between the lithotrite electrodes. In the lines connecting the pulse forming network to the lithotrites, the prior art instruments include spark gaps. These gaps have the disadvantages of being temperature and humidity dependent and of providing a great deal of service and maintenance problems. In accordance with the invention, the spark gaps are replaced by solid state switch devices such as thyristors. The switching devices are controlled by a solid state pulse generator, and the repetition rate and intensity of the electrical discharges can be varied by varying the repetition rate and pulse duration of the pulse generator.

United States Patent [191 Shene Sept. 2, 1975 STONE DISINTEGRATOR [75]Inventor: William Richard Shene, Plattsburgh,

[73] Assignee: Saul Hoffman, Montreal, Canada [22] Filed: Jan. 2, 1974[21] Appl. No.: 429,484

[52] US. Cl 128/328; 128/421 [51] Int. Cl A61b 17/22; A6ln 1/06; A6lnl/08 [58] Field of Search 128/328, 421

[56] References Cited UNITED STATES PATENTS 2,609,499 9/1952 Gilson128/421 X 3,557,793 1/1971 Ediny, et a1... 128/328 3,735,764 5/1973Balev et a1. 128/328 3,746,005 7/1973 Thaler et al. 128/421 X 3,746,0067/1973 Thaler 128/421 X 3,782,389 l/l974 Bell 128/421 X FOREIGN PATENTSOR APPLICATIONS 1,218,112 6/1966 Germany 128/328 PrimaryExaminer-Channing L. Pace Attorney, Agent, or Firm-Robert Mitchell;Arthur Schwartz; David A. Blumenthal ABSTRACT This invention relates toan instrument for disintegrating calculi in the urinary tract byhydraulic impacts formed by electrical discharges in the liquid mediumsurrounding the calculi. Instruments employing this general principleare well known and they usually consist of a lithotrite having twoelectrodes, and a pulse forming network connected to the electrodes toprovide electrical energy for forming discharge between the lithotriteelectrodes. In the lines connecting the pulse forming network to thelithotrites, the prior art instruments include spark gaps. These gapshave the disadvantages of being temperature and humidity dependent andof providing a great deal of service and maintenance problems. Inaccordance with the invention, the spark gaps are replaced by solidstate switch devices such as thyristors. The switching devices arecontrolled by a solid state pulse generator, and the repetition rate andintensity of the electrical discharges can be varied by varying therepetition rate and pulse duration of the pulse generator.

PATENTEDSEP '2I975 3,902,499

sum 1 or 3 PATENTEU SEP 2 I975 SHEET 2 hN J STONE DISINTEGRATORBACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to an instrument for disintegrating calculi in the urinary tractby hydraulic impacts formed by electrical discharge in the liquid mediumwhich surrounds the calculi, wherein capacitors, which chargelithotrites to form the electrical discharge, are discharged throughcircuits employing solid state devices.

2. Statement of the Prior Art It is known in the art to use hydraulicimpacts due to electrical discharge to disintegrate calculi in theurinary tract as is shown in US. Pat. No. 3,557,793, issued Jan. 26,I97], .I. G. Ediny et al, inventors, and US. Pat. No. 3,735,764, issuedMay 29, 1973, O. G. Balev et al, inventors. However, in both of thesepatents, the capacitors of the charging circuit for charging theelectrodes of the lithotrites consist of spark gap arrangements. Thespark gaps have the disadvantages of being temperature and humiditydependent so that, with the same setting on the output of theinstruments, different intensity and frequency of hydraulic shock waveswill be provided under different temperature, humidity and conditions.In addition, the spark gaps of the instruments require more service andmaintenance than any other parts.

SUMMARY OF THE INVENTION In order to overcome the disadvantages of theinstruments known in the art, an instrument is provided wherein thespark discharge circuits employ solid state devices. Specifically, thesolid state devices employed are solid state switches, preferablyswitches known as thyristors.

The thyristors are driven by a solid state pulse generator. In this way,the pulse width and frequency of the driving signal can be madecontinuously variable, and it is also possible to provide a digitalreadout of the signal driving the switches.

By varying the pulse width and frequency of the pulse generator, theintensity and repetition rate of the lithotrite discharge is madeadjustable, and the different intensity and discharge rates can be madeselectable by providing appropriate switches on the front face of theinstrument.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be betterunderstood by an examination of the following description together withthe accompanying drawings, in which:

FIG. 1 is a front view of an instrument front panel in accordance withthe invention and including various items for connection thereto;

FIG. 2 is a block diagram in schematic form of the circuit for operatingand controlling the instrument;

FIG. 3 is a circuit diagram in schematic form of the circuit foroperating and controlling the instrument;

FIG. 4 is a preferred form of the lithotrite in accordance with theinvention; and V FIGS. 4a and 4b are detailed views of the lithotrite ofFIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, theinstrument is designated generally at l and comprises a front panel 3.The instrument preferably includes a foot pedal switch 5, the purpose ofwhich will be discussed below. Connecting cables 7 and 9 constitute theremaining required peripheral items.

The front panel includes a continuously variable intensity-adjustingcontrol 11. Varying the control 11 will change the pulse width of asolid state pulse generator as will be discussed in relation to FIGS. 2and 3, and the meter 12 gives a digital indication of the pulse widthand the frequency of the pulse generator. Power is switched to theinstrument through ON/OFF switch 13, and lamp 15 is turned on when poweris switched on. Power is brought to the instrument through power cable7, which is plugged in, at one end, to a wall socket for 1 17V 60 Hz,and at the other end to socket 17 in the instrument. Socket 19 receivesthe plug at the end of the foot pedal switch cable. When the foot pedalswitch 5 is activated, a circuit is completed to cause electricaldischarges as will be discussed below. At the same time, lamp 21 will beturned on. Switch 10 selects the interval of continuous operation of theinstrument as will be explained below.

Solid state switches (not shown) are connected to terminals 23 and 25.Connectors 9a and 9b on cable 9 are connected to terminals 23 and 25.The other end of cable 9 contains a lithotrite.

Fuse 27 is included with the instrument for purposes of safety as iswell known to one skilled in the art.

The front face of the instrument also includes a ground fault indicatorlight 20.. This light will come on whenever there is a ground fault inthe instrument.

Referring now to FIG. 2, the circuit consists of an EMI filter 29 whichreceives the input power from plug 17. The power is supplied, throughON/OFF switch 13, to solid state pulse generator 53. The solid statepulse generator contains controls for varying the frequency of the pulsegenerator as well as the pulse duration of each cycle as is well knownin the art. In addition, the solid state pulse generator will drivedigital readout meters to give a visual readout of both the pulsefrequency and the pulse duration.

The input voltage from the EMI filter is also applied, in a parallelarrangement, to timer relay 49. Relay 49 controls the operation ofswitch 50, consisting of two parts 50a and 50b. A third parallel pathprovides power to the lamps 15 and 21. As can be seen, the lamp 15 willbe turned on when switch 13 is closed. Lamp 21 requires that both switch13 and switch 50b be turned on before this lamp will be turned on.

In a third parallel arrangement, power is applied to transformer 33. Theoutput winding of transformer 33 is connected to a pulse forming networkindicated generally at 34. The pulse forming network consists of a fullwave rectifier made up of diodes 35 and 37. Capac itors 40 and 42 arecharged through resistors 39 and 41 respectively to provide outputpulses Preferably, 39 is equal in value to 41, and 40 is equal in valueto 42 so that time constant of 39 and 40 is equal to the time constantof 41 and 42.

The common lead of the pulse forming network is connected, through solidstate switch means 55 to ter minal 23. The outer conductor of thelithotrite (see FIG. 4) is connected to terminal 23. The hot line of thepulse forming network is connected to terminal 25 through means 55. Thecenter conductor of the lithotrite is connected to 25. Lead 54 connectsthe output of the solid state generator to the solid state switch means55.

As can be seen in FIG. 3, the solid state switch means preferablycomprises thyristors 55a and 55b. The output of the solid stategenerator is connected to the gate electrodes of the thyristors. As iswell known in the art, when a gating signal (a pulse from the solidstate pulse genera-tor) is supplied to the gate electrodes of thethyristors, then the thyristors are in the ON state and the output ofthe pulse forming network 34 is applied to terminals 23 and 25.

Although two thyristors are shown, it is of course realized that it maybe possible to use only one thyristor in either one of the lines.Alternately, the two thyristors could be connected in series in the sameline.

DC for driving the solid state generator is preferably provided fromstep-down transformer 32 and bridge rectifier 33 as is well known in theart. The ground fault indicator 51 preferably comprises pairs of triacand resistor combinations 52, 53 and 54, 55. In addition, an indicatorlight 20 is included in the ground fault indicator circuit.

Bleeding resistors 43 and 45 are safety devices as is known in the art.

The timer relay 49 is preferably one of the type which latches for agiven period of time, as determined by the setting on timing device 490,before releasing. In the preferred embodiment, the relay will latch forperiods of l, or l0 seconds. It is of course understood that differentlatching periods could be selected, and that the latching period couldbe made continuously selectable rather than discretely selectable assuggested in the above. Timing relays of this nature are well known inthe art and require no further description here.

In operation, the circuit works as follows: When switch 13 is closed,power is provided to lamp so that this lamp turns on. At the same time,power is provided to the input windings of transformer 32. When theswitch 5 is closed (by stepping on the foot pedal) power is supplied torelay 49 so that the parts 50a and 50b of the switch 50 are closed. Thisprovides power to the lamp 21 to turn it on, and at the same time,allows the output of the pulse generator 53 to be fed to thyristors 55aand 55b.

The voltage at the input to 33 is stepped up, and the output of thetransformer is applied to the pulse forming network. Capacitors 40 and42 charge up through their respective charging resistors 39 and 41 untilthey reach a voltage sufficient to cause a spark across the spark gapplates. The capacitors will, of course, be discharged through thethyristors when the thyristors are in the ON state i.e., when pulses areapplied to their gate electrodes to provide pulses. The pulses, formedby the pulse forming networks, are then passed to the electrodes of thelithotrites, and a spark is discharged between these electrodes in themedium surrounding the calculi. This is what causes the electrohydraulicimpact.

The intensity of the electrical discharge caused by the spark dischargeis varied by varying the pulse width of the pulses of the generator 53.Decreasing the pulse width will decrease the intensity of the electricaldischarge and vice-versa.

The repetition rate of the discharges is controllable by varying thefrequency of the solid state pulse generator. There will, of course, bea one to one relationship between the repetition rate of the generatorand the repetition rate of the discharges.

A series of discharges will take place for the full period as set by thetiming relay 49. After this full period has elapsed, in order torecornmence operation, it will be necessary to once again step on thefoot pedal. The light 21 on the front panel will light up whenever theinstrument is in operation and will be extinguished when relay 49releases to open switches 50a and 50b.

In considering the operation of the ground fault indicator 51, it isclear that, when there is a ground available, light 20 will not be litup. However, when there is no ground, then triacs power will passthrough the light 20, and this condition will then be indicated on thefront face of the instrument and power to the instrument will beremoved.

It will be appreciated that different combinations of intensity andrepetition rate will have different effects on the calculi under attack.Thus, it is noted that round smooth calculi can be more quickly attackedfor an initial fissure by providing a high intensity, lower repetitionrate discharge. Other shapes and form of calculi may be moresuccessfully attacked with different combinations.

A lithotrite for use with the inventive instrument is illustrated inFIG. 4. The lithotrite is generally indicated as 152 and is shownattached to the connecting cable 9. It consists of an outer conductorsleeve 153, insulation 154, center conductor 155 and outer insulation157. In accordance with a preferred embodiment of the invention, fingers156 extend from the end of the lithotrite. The fingers are preferablyflexible and transparent and are used to retain the calculi when theinstrument is in use. As shown in FIG. 4b, the fingers are made of thesame material as the outer insulation 157. As smooth calculi have atendency to roll away when subjected to an electrical discharge, the useof the flexible fingers will retain the calculi close to the dischargeso that the full effect of the discharge will be felt by the calculi.This could shorten the time required to disintegrate the calculi.

In operation, the instrument is used in association with a cystoscopeequipped with fibre optics. The lithotrite is inserted in the urinarybladder, which is filled with washing fluid. The lithotrite is thenvisually manipulated until the top of the lithotrite 152 is in contactwith the calculus. The flexible fingers 156 tend to keep the lithotritefrom slipping off the stone, especially a smooth stone. Power will havebeen turned on beforehand, so that it will merely be necessary for theoperator to step on foot pedal switch 5 to initiate an electricaldischarge in the fluid medium surrounding the calculus.

If the calculus is smooth or large, the intensity of the discharge willbe made high by adjusting the control 11 on the front panel of theinstrument. When initial fissures in the calculus are noted, theintensity can be turned down. Electrical discharges are applied untilthe calculus is so disintegrated that it can be removed by flushing.

Although a specific embodiment has been discussed in the foregoing, thiswas for the purpose of describing, but not limiting, the invention.Various modifications, which will come readily to the mind of oneskilled in the art, are within the scope of the invention as defined inthe appended claims.

I claim:

I. An instrument for attacking calculi in liquid medium surrounding thecalculi, comprising:

lithotrite means comprising a first electrode and a second electrodespaced from said first electrode;

means for providing electrical energy to said electrodes to cause aspark discharge between said first and second electrodes in said liquidmedium, said means comprising capacitive storage means connected to afirst output terminal and a second output terminal;

a first lead connecting said first output terminal to said firstelectrode and a second lead connecting said second output terminal tosaid second electrode;

a first solid state switch in said first lead between said first outputterminal and said first electrode;

a second solid state switch in said second lead between said secondoutput terminal and said second electrode; and

pulse generator means connected to said first and second solid stateswitches for providing control signals to said first and second solidstate switches, said pulse generator means having means fo'rrvarying thepulse duration and the pulse repetition rate of said control signals.

2. An instrument as defined in claim 1 wherein said solid state switchescomprise thyristors having gate electrodes and said pulse generatormeans is connected to the gate electrodes of said thyristors;

whereby the intensity and repetition rate of said spark discharge arevariable.

3. An instrument for attacking calculi in the urinary tract byelectro-hydraulic impacts in a liquid medium surrounding the calculi,comprising:

a pulse forming network having an input circuit for 6 '7 receiving inputvoltage to said pulse forming network; 7 said pulse forming networkcomprising capacitive storage means connected to two output leads; solidstate switch means in each of said output leads; said instrument furthercomprising a lithotrite having a first electrode and a second electrodespaced from said first electrode;

means for connecting one of said output leads to said first electrode;

means for connecting the other output lead to said second electrode; and

pulse generator means connected to said solid state switch means forproviding control signals to said solid state switch means, said pulsegenerator means having means for varying the pulse duration and pulserepetition rate of said control signals.

4. An instrument as defined in claim 3 wherein said solid state switchescomprise thyristors having gate electrodes and said pulse generatormeans is connected to the gate electrodes of said thyristors;

whereby the intensity and repetition rate of said spark discharge arevariable.

5. An instrument'as defined in claim 3, wherein said first and secondelectrodes of said lithotrite are coaxially arranged;

said first electrode comprising an inner conductor in said co-axialarrangement;

and said second electrode comprising an outer conductor in said co-axialarrangement.

6. An instrument as defined in claim 5, wherein said lithotritecomprises flexible fingers extending therefrom.

1. An instrument for attacking calculi in a liquid medium surroundingthe calculi, comprising: lithotrite means comprising a first electrodeand a second electrode spaced from said first electrode; means forproviding electrical energy to said electrodes to cause a sparkdischarge between said first and second electrodes in said liquidmedium, said means comprising capacitive storage means connected to afirst output terminal and a second output terminal; a first leadconnecting said first output terminal to said first electrode and asecond lead connecting said second output terminal to said secondelectrode; a first solid state switch in said first lead between saidfirst output terminal and said first electrode; a second solid stateswitch in said second lead between said second output terminal and saidsecond electrOde; and pulse generator means connected to said first andsecond solid state switches for providing control signals to said firstand second solid state switches, said pulse generator means having meansfor varying the pulse duration and the pulse repetition rate of saidcontrol signals.
 2. An instrument as defined in claim 1 wherein saidsolid state switches comprise thyristors having gate electrodes and saidpulse generator means is connected to the gate electrodes of saidthyristors; whereby the intensity and repetition rate of said sparkdischarge are variable.
 3. An instrument for attacking calculi in theurinary tract by electro-hydraulic impacts in a liquid mediumsurrounding the calculi, comprising: a pulse forming network having aninput circuit for receiving input voltage to said pulse forming network;said pulse forming network comprising capacitive storage means connectedto two output leads; solid state switch means in each of said outputleads; said instrument further comprising a lithotrite having a firstelectrode and a second electrode spaced from said first electrode; meansfor connecting one of said output leads to said first electrode; meansfor connecting the other output lead to said second electrode; and pulsegenerator means connected to said solid state switch means for providingcontrol signals to said solid state switch means, said pulse generatormeans having means for varying the pulse duration and pulse repetitionrate of said control signals.
 4. An instrument as defined in claim 3wherein said solid state switches comprise thyristors having gateelectrodes and said pulse generator means is connected to the gateelectrodes of said thyristors; whereby the intensity and repetition rateof said spark discharge are variable.
 5. An instrument as defined inclaim 3, wherein said first and second electrodes of said lithotrite areco-axially arranged; said first electrode comprising an inner conductorin said co-axial arrangement; and said second electrode comprising anouter conductor in said co-axial arrangement.
 6. An instrument asdefined in claim 5, wherein said lithotrite comprises flexible fingersextending therefrom.